Fastener forming machine

ABSTRACT

A fastener forming apparatus comprises a positive stop that prevents workpieces from overshooting the end of a forming stroke. A workpiece transfer mechanism transfers one unformed workpiece at a time into a workpiece gripper and drives completed workpieces out of the workpiece gripper and onto an exit path. A compound hydro-pneumatic cylinder moves the gripper and one workpiece at a time downward into contact with a rotating forming tool. A knurled ring is adjustably supported on a threaded portion of a lower piston of the hydro-pneumatic cylinder in a position to contact a stationary stop surface when the workpiece gripper and tool reach the end of the forming stroke, halting the downward motion of the workpiece. The ring also actuates a lower limit switch at the stationary stop surface which causes the reciprocator to reverse direction. The forming tool includes a tool adapter head that holds various forming implements such as cutting blades or drill bits. The head also accommodates broachers and reamers, in which case a precision logic control detects and rejects defective workpieces that have no holes to broach or ream.

TECHNICAL FIELD

This invention relates generally to a fastener-forming machine and, moreparticularly, to a secondary fastener-forming machine.

BACKGROUND OF THE INVENTION

Secondary fastener forming machines take cylindrical workpieces, such asheaded fastener blanks that have been formed in a primary fastenerforming process, and perform additional operations on the workpiecessuch as tapering the ends. To perform additional operations such aspointing on the blanks, some secondary forming machines drive the blanksaxially along a linear forming stroke into engagement with cuttersmounted on a cutting head. It is highly desirable that secondaryfastener forming machines of this type include means for adjusting thelength of each forming stroke to accommodate fastener blanks and otherworkpieces of various lengths. It is also desirable that such machinesinclude a mechanism that senses when a blank has reached the end of itsforming stroke and causes the machine to reverse and disengage theformed workpiece from the forming tool.

Optical Boring Company, the assignee of the present invention,manufactures a secondary fastener forming machine (the OBC machine) thatforms pointed ends onto headed fastener blanks. The OBC machine includesa reciprocator in the form of a 2-piston hydro-pneumatic cylinder thatreciprocates a reciprocating portion of the assembly including afastener gripper upward to a fully retracted "remote" position anddownward through a cutting stroke to a fully extended "proximate"position. During the lower portion of the cutting stroke the lower endof a fastener blank held in the gripper axially engages a rotatingcutting tool at a cutting tool rotational axis. The cutting toolincludes carbide cutting blades that are positioned around the cuttingtool axis to cut a tapered conical tip on the fastener blank. One pistonwithin the cylinder is hydraulically dampened leaving no hard linkagesbetween the forming machine and the fastener blank being worked. Thislack of hard linkages allows the downward travel of the fastener blankand gripper to slow with increased resistance during the cutting strokeand to slow further or even stop completely in response to excessiveresistance. After cutting, the cylinder lifts the gripper and extractsthe fastener from the cutting tool, completing a cutting cycle. The OBCmachine also includes a part transfer mechanism that inserts and ejectsparts. The reciprocal motion of one of the pistons within thehydro-pneumatic cylinder drives the part transfer mechanism.

An adjustable screw axially engages a limit switch whenever a fastenerhas reached the end of its forming stroke. When the limit switch is thusactivated it signals the reciprocator to reverse the reciprocatingportion of the assembly and disengage the newly-tipped fastener from thecutters. The screw may be advanced or retracted to adjust the reversalpoint of the cylinder at the end of the cutting stroke.

While a reciprocator of this type provides many advantages it cannotconsistently terminate the downward forming/cutting stroke at the sameproximate position within acceptable tolerances. If cycle speed isincreased for any reason, the reciprocating portion of the assembly andthe fastener blank can overshoot the proximate position resulting in adeeper cut on the fastener. Conversely, if cycle speed decreases for anyreason, the reciprocating portion may undershoot the desired reversalpoint resulting in a shallower cut on the fastener. Cycle speed willtend to decrease over time as the cutters begin to get dull fromrepeated cutting cycles. The cycle speed slows because the forcerequired to advance each fastener blank into the cutters increases whilethe pneumatic pressure supply remains relatively constant. In addition,small variations in pneumatic pressure supply are common with mostindustrial air compressor systems and can result in cutting depthvariations that are unacceptable in certain applications.

What is needed is a hydro-pneumatically driven fastener forming machinethat, without hard linkages, moves fastener blanks through a formingstroke while positively and consistently maintaining the end-of-strokestopping position, i.e., the "proximate" position of each workpiecerelative to the forming tool. What is also needed is such a machine thatcan accommodate bolts of various lengths.

SUMMARY OF THE INVENTION

In accordance with the present invention a hydro-pneumatically drivenfastener forming apparatus for forming fasteners from cylindricalworkpieces comprises a positive stop. The positive stop prevents areciprocating portion of the apparatus from causing workpieces toovershoot or undershoot a proximate position relative to a forming tool.The apparatus includes a workpiece gripper supported for reciprocalmovement along a forming axis and configured to releasably grip andcarry a generally cylindrical workpiece in a coaxial disposition alongthe forming axis. The forming tool is spaced from the gripper along theforming axis. At least one of the part gripper and tool is supported forrelative reciprocal motion along the axis between a remote position andthe proximate position. The gripper and tool are disposed farther apartin the remote position than in the proximate position. The assembly alsoincludes a workpiece transfer mechanism configured to sequentiallytransfer a series of workpieces into the workpiece gripper and to drivepreceding workpieces out of the workpiece gripper and onto an exit path.A reciprocator is operatively connected to the reciprocating portion ofthe apparatus. The reciprocating portion of the apparatus comprises oneof the workpiece gripper and tool. The reciprocator drives one of theworkpiece gripper and tool between the extended and retracted positions.The reciprocator has a stationary end connected to a stationary supportand a reciprocating end operatively connected to the reciprocatingportion of the apparatus. The stationary end is hydro-pneumaticallycoupled to the reciprocating end. The motion of the reciprocating endand the reciprocating portion of the apparatus are hydraulicallydampened. The positive stop includes a reciprocating stop surfacedisposed on the reciprocating portion of the apparatus in a position toengage a stationary stop surface when the workpiece gripper and tool arein the proximate position.

In accordance with another aspect of the invention the reciprocatingstop surface is disposed on a reciprocating stop that is adjustablyconnected to the reciprocating portion of the apparatus. The position ofthe reciprocating stop relative to the reciprocating portion of theapparatus is adjustable in a direction parallel to the forming axis toallow an operator to adjust the extended position.

In accordance with another aspect of the invention the reciprocatorincludes a lower limit switch disposed in the path of the reciprocatingportion of the apparatus. The lower limit switch is actuable by contactwith the reciprocating portion of the apparatus in the extendedposition. The lower limit switch is configured to send a signal inresponse to actuation that causes the reciprocator to reverse direction.

In accordance with another aspect of the invention the lower limitswitch is supported adjacent the stationary stop. The lower limit switchincludes a plunger actuator that extends through an aperture in thestationary stop surface.

In accordance with another aspect of the invention the reciprocatorincludes a compound hydro-pneumatic cylinder connected between thestationary end and the reciprocating end of the reciprocator.

In accordance with another aspect of the invention the hydro-pneumaticcylinder is connected to a stationary support. A reciprocating pistonrod extends from a piston within the cylinder and operatively connectsto the workpiece gripper.

In accordance with another aspect of the invention reciprocal motion ofthe reciprocator drives the workpiece transfer mechanism.

In accordance with another aspect of the invention a rotator isoperatively connected to one of the workpiece gripper and the tool torotate one of the workpiece gripper and the tool about the axis.

In accordance with another aspect of the invention the tool is supportedon the rotator to rotate the tool about the axis and the gripper issupported on the reciprocator.

In accordance with another aspect of the invention the tool includescutters disposed adjacent the axis in a position to cut one end of aworkpiece held in the gripper as the gripper and cutting tool approachthe proximate position.

In accordance with another aspect of the invention the tool includes adrill aligned with the axis in a position to drill a hole into one endof a workpiece held in the gripper as the gripper and cutting toolapproach the proximate position.

In accordance with another aspect of the invention the tool includes abroacher aligned with the axis in a position to broach a hole preformedinto one end of a workpiece held in the gripper as the gripper andcutting tool approach the proximate position.

In accordance with another aspect of the invention the forming implementis an implement that alters the configuration of a previously formedhole in a workpiece, and the assembly includes an electronic controllerconfigured to detect workpieces that lack the previously formed hole.The electronic controller may comprise a precision logic control that isprogrammed to cause the assembly to reject workpieces by, for example,opening a wastegate in the exit chute. The precision logic control maybe programmed to detect the absence of a hole when the forming stroketakes longer than a predetermined maximum time.

In accordance with another aspect of the invention the tool includes atool adapter head configured to releasably engage forming implements.

In accordance with another aspect of the invention the tool adapter headincludes a pair of cutter receptacles for releasably engaging cutters.

In accordance with another aspect of the invention the tool adapter headincludes a chuck receptacle for releasably engaging a collet chuck forsupporting drill bits, broachers and the like.

In accordance with another aspect of the invention the assembly includesa height adjuster connected between the reciprocating portion and thestationary portion. The height adjuster is configured to allow anoperator to adjust forming depth by adjusting the relative distancebetween the reciprocating and stationary portions as measured along theforming axis in the proximate position.

In accordance with another aspect of the invention the assembly includesa sorter attachment comprising an electrically-conductive ring coaxiallysupported on the forming tool and coaxially aligned with and spaced fromthe part gripper. The ring is pre-selected to have an inner diameterslightly larger than an outer diameter of a series of workpieces to besorted. The ring is configured to encircle a portion of a relativelystraight workpiece held in the gripper when the gripper and ring are inthe proximate position, the workpiece being withdrawn from the ring whenthe gripper and ring are in the remote position. The ring, support frame36, reciprocator, gripper and a workpiece held in the gripper define anopen electrical circuit that is closed only when a workpiece contactsthe ring. An electrical power source is connected into the circuit. Anelectrically actuated workpiece diverter is also connected into thecircuit and is mechanically supported adjacent the workpiece exit path.The workpiece diverter is operable to shunt bent workpieces away fromthe exit path when the bent workpieces contact the ring and complete theelectrical circuit.

BRIEF DESCRIPTION OF THE DRAWINGS

To better understand and appreciate the invention, refer to thefollowing detailed description in connection with the accompanyingdrawings:

FIG. 1 is a perspective view of a fastener forming apparatus constructedaccording to the invention;

FIG. 2 is a fragmentary partially broken-away front view of the fastenerforming apparatus of FIG. 1;

FIG. 3 is a fragmentary top view of a workpiece transfer portion of thefastener forming apparatus of FIG. 1;

FIG. 4 is a perspective view of a forming tool adapter head of thefastener forming apparatus of FIG. 1 with cutting blocks installed;

FIG. 5 is a perspective view of the forming tool adapter of FIG. 4 withcutting blocks removed and a collet chuck and drill bit installed;

FIG. 6 is a perspective view of a block portion of a positive stopfeature of the fastener forming apparatus of FIG. 1;

FIG. 7 is a fragmentary partially broken-away front view of the fastenerforming apparatus of FIG. 1 with upper and lower pistons of a compoundhydro-pneumatic cylinder of the apparatus at the top of their respectivetravels;

FIG. 8 is a fragmentary partially broken-away front view of the fastenerforming apparatus of FIG. 1 with the upper pistons of the compoundhydro-pneumatic cylinder positioned part way downward on the initialportion of a downward forming stroke;

FIG. 9 is a fragmentary partially broken-away front view of the fastenerforming apparatus of FIG. 1 with upper and lower pistons of a compoundhydro-pneumatic cylinder of the apparatus at the bottoms of theirrespective travels at the end of the downward forming stroke;

FIG. 10 is a partially cut-away, partial cross-sectional front view of apneumatic slide lift feature of the fastener forming apparatus of FIG.1;

FIG. 11 is a block diagram of a precision logic control feature of thefastener forming apparatus of FIG. 1;

FIG. 12 is a diagrammatic side view of the fastener forming apparatus ofFIG. 1 with a wastegate feature installed; and

FIG. 13 is a fragmentary diagrammatic top detail view of region "A" inFIG. 12 showing the wastegate feature of the fastener forming apparatusof FIG. 12.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A fastener forming apparatus for forming fasteners from headedcylindrical workpieces 16 is generally shown at 10 in FIG. 1. Theapparatus 10 comprises a workpiece gripper or grip chuck, generallyindicated at 12 in FIGS. 1,2 and 7-9. The grip chuck 12 is supported forreciprocal movement along a forming axis shown at 14 in FIGS. 1-9. Thereciprocal movement includes alternating downward cutting strokes andupward return strokes. The grip chuck 12 is configured to releasablygrip and carry a generally cylindrical workpiece 16 in a coaxialdisposition along the forming axis 14. A forming tool, generally shownat 18 in FIGS. 1, 2, 4, 5 and 9, is spaced vertically below the gripchuck 12 along the forming axis 14. The grip chuck 12 is supported forreciprocal motion along the forming axis 14 between a remote positionshown in FIG. 7 and a proximate position shown in FIG. 9. As shown inFIGS. 7 and 9, the grip chuck 12 and forming tool 18 are disposedfarther apart in the remote position than in the proximate position. Inthe proximate position shown in FIG. 9 the workpiece is engaged with theforming tool 18 and is at the end of its downward cutting stroke.

The apparatus 10 also includes a workpiece transfer mechanism 20generally indicated at 20 in FIGS. 1-3. The workpiece transfer mechanism20 is configured to sequentially drive formed workpieces 16 out of thegrip chuck 12 by transferring unformed workpieces 16 into the grip chuck12 when the grip chuck 12 is in the remote position. The formedworkpieces 16 are driven from the grip chuck 12 onto an exit chute shownat 22 in FIG. 3. The transfer mechanism 20 receives workpieces 16 from aspiral track (not shown) in a vibrating bowl 24 that feeds theworkpieces 16 into a downwardly sloping load chute 26. The workpiecesslide by gravitational force down the sloping load chute 26 to a level"landing" portion 28 of the load chute 26. The landing portion 28 of theload chute 26 is disposed adjacent the transfer mechanism 20, tangentialto the forming axis 14 and is spaced from the forming axis 14.

A reciprocator in the form of a compound hydro-pneumatic cylinder,generally indicated at 30 in FIGS. 1, 2 and 7-9, is operativelyconnected to a reciprocating portion of the apparatus 10 generallyindicated at 32 in FIGS. 1, 2 and 7-9. The reciprocating portion 32 ofthe apparatus 10 comprises the grip chuck 12. The hydro-pneumaticcylinder 30 drives the grip chuck 12 and workpiece 16 between theextended and retracted positions. Reciprocal motion driven by thecompound cylinder 30 also operates the workpiece transfer mechanism 20.The compound hydro-pneumatic cylinder 30 has a stationary end shown at34 in FIGS. 1, 2 and 7-9 that is connected to a stationary support frame36. The compound hydro-pneumatic cylinder 30 has a reciprocating end inthe form of a piston rod shown at 38 in FIGS. 2 and 7-9. The piston rod38 is operatively connected to the reciprocating portion 32 of theapparatus 10 at the grip chuck 12. As is described in greater detailbelow, the piston rod 38 is hydro-pneumatically coupled to the supportframe 36 through the compound hydro-pneumatic cylinder 30 for a portionof its downward travel on the forming stroke. Therefore, for thatportion of the forming stroke, the motion of the piston rod 38 and thegrip chuck 12 is hydraulically dampened.

The apparatus 10 also comprises a down-stroke positive stop generallyindicated at 40 in FIGS. 2 and 7-9. The positive stop 40 includes areciprocating stop surface and a stationary stop surface shown at 42 and44, respectively, in FIGS. 2 and 7-9. The reciprocating stop surface 42is disposed on the reciprocating portion 32 of the apparatus 10 in aposition to engage the stationary stop surface 44. The stationary stopsurface 44 is supported on a portion of the stationary support frame 36in vertical alignment with the reciprocating stop surface 42 when thegrip chuck 12 and tool 18 are in the proximate position. The positivestop 40 prevents the compound hydro-pneumatic cylinder 30 from causingthe reciprocating portion 32 of the apparatus 10 to overshoot theextended position which prevents workpieces 16 from advancing too farinto the forming tool 18 and being over-cut.

The compound hydro-pneumatic cylinder 30 is connected between thestationary support frame 36 and the reciprocating end of thereciprocator, i.e., the piston rod 38. The compound pneumatic-hydrauliccylinder 30 reciprocates the workpiece 16 and the grip chuck 12 throughthe downward forming stroke and the upward return stroke with theworkpiece 16 moving along the forming axis 14. The compoundhydro-pneumatic cylinder 30 is pneumatically driven through an upperpiston shown at 46 in FIGS. 7-9. The upper piston 46 is mounted within apneumatic cylinder 48 of the compound cylinder 30 and is hydraulicallydampened for a portion of the forming stroke by an annular lower pistongenerally indicated at 50 in FIGS. 2 and 7-9. The lower piston 50 isslidably supported within a hydraulic cylinder 52 of the compoundcylinder 30.

As best shown in FIG. 2, the piston rod 38 extends downward from theupper piston 46 and operatively connects to the grip chuck 12. Thepiston rod 38 is fastened to the upper piston 46 and is slidablydisposed through upper and lower tubular channels 54, 56 of the annularlower piston 50. The upper tubular channel 54 is shown in FIGS. 7-9 andthe lower tubular channel is shown in FIG. 2. The tubular channels 54,56 each includes at least one O-ring seal 57. The O-ring seals 57provide fluid-tight seals between the lower piston 50 and the piston rod38. As shown in FIGS. 7-9, a lower end 58 of the piston rod 38 passesthrough an upper guide hole 60 in a generally rectangular bronze guideplate 62 that is supported on the support frame 36. The lower end 58 ofthe piston rod 38 then passes through a lower guide hole 64 in a steelcross bar portion 66 of the grip chuck 12 and connects to a plunger 68.

As shown in FIGS. 2, 3 and 7-9, the plunger 68 is slidably disposedwithin the lower guide hole 64 in the cross bar portion 66 of the gripchuck 12. The plunger 68 is configured to engage both a top surface orhead of the unformed workpiece 16 and laterally inwardly extending armportions 70 of a pair of opposing grip jaws 72. The grip jaws 72 aremounted to the cross bar 66 via parallelogram-type linkages 74. Theparallelogram linkages 74 support the grip jaws 72 in such a way thatdownward pressure from the plunger 68 forces the jaws 72 downward inrelation to the cross bar 66 and inward in relation to each other andinto an over-center "gripped" position. In the gripped position, thegrip jaws 72 clamp onto the shaft portion of an unformed workpiece 16positioned between them. The grip jaws 72 are shown in the grippedposition in FIGS. 2, 3, 8 and 9. Conversely, the plunger 68 isconfigured to draw upward on the laterally inwardly extending armportions 70 of the grip jaws 72 on the return stroke, moving the gripjaws 72 over-center to their open position and releasing the workpiece16 positioned between them. The grip jaws 72 are shown in their openposition in FIG. 7.

An upper air supply tube shown at 76 in FIG. 1 connects a solenoid airdiverter valve 78 to an upper portion of the pneumatic cylinder 48 abovethe upper piston 46. A lower air supply tube 80 connects the solenoidair diverter valve 78 to a lower portion of the pneumatic cylinder 48below the upper piston 46. The diverter valve 78 is electricallyactuated to alternately direct pressurized air through the upper andlower air supply tubes 76, 80 and into upper and lower portions of thepneumatic cylinder 48, respectively. Air directed to the upper portionof the pneumatic cylinder 48 forces the upper piston 46 downward on theforming stroke. Air directed to the lower portion of the pneumaticcylinder 48 forces the upper piston 46 upward on the return stroke.

A cylinder wall 82 of the hydraulic cylinder 52 is supported on aportion of the support frame 36 that is connected to the stationarybronze guide plate 62. The lower piston 50 includes a generallydisk-shaped portion 84 and a cylindrical portion 86 that extendsconcentrically and integrally downward from the disk-shaped portion 84to the cross-bar portion 66 of the grip chuck 12. The cylindricalportion 86 of the lower piston 50 concentrically surrounds the pistonrod 38 and is fastened to the cross-bar portion 66 of the grip chuck 12at a lower end of the cylindrical portion 86.

The outer circumference of the cylindrical portion 86 of the lowerpiston 50 is smaller than an outer circumference of the disk-shapedportion 84 and defines a hydraulic oil-filled annular chamber 88. Theannular chamber 88 is disposed between an outer cylinder wall 90 of thehydraulic cylinder 52 and an outer surface of the cylindrical portion 86of the lower piston 50. An upper O-ring seal 57A is supported in arecess formed into the outer circumference of the lower piston 50. Theupper O-ring seal 57A seals the disk-portion 84 of the lower piston 50against the hydraulic cylinder wall 90. A lower O-ring seal 57B issupported in a recess formed into an inner circumference of a circularaperture 92 in the support frame 36. The lower O-ring seal 57B seals thecircular aperture in the support frame 36 against the cylindricalportion 86 of the lower piston 50. The upper and lower O-ring seals 57A,57B cooperate to prevent hydraulic oil from escaping the annular chamber88.

As shown in FIGS. 1, 2 and 7-9, a metal hydraulic tube 94 connects theannular chamber 88 of the hydraulic cylinder 52 and apneumatically-pressurized hydraulic reservoir 98 that is supported onthe pneumatic cylinder 48. The hydraulic tube 94 provides a fluidchannel between the annular chamber 88 and the hydraulic oil reservoir98. The hydraulic oil reservoir 98 is pressurized by air delivered froma pressurized air source (not shown) through a reservoir air supply tubeshown at 100 in FIG. 1. A manually-adjustable Parker hydraulic dampeningvalve (part no. F600B) 102 is connected approximately midway along thelength of the hydraulic tube 94. The dampening valve 102 is configuredto adjustably restrict only the flow of hydraulic oil from the annularchamber 88 to the reservoir 98. The dampening valve 102 does notrestrict oil flow from the reservoir 98 to the annular chamber 88.Because the lower piston 50 is hydraulically dampened and no hardlinkages exist between the stationary support frame 36 and the workpiece16, the reciprocal motion of the compound hydro-pneumatic cylinder 30slows with increased resistance and stops with too much resistancerather than jamming or breaking.

As explained above, a vibrating bowl 24 feeds unformed workpieces 16into a downwardly sloping load chute 26. The workpieces 16 come to restin a level landing portion 28 of the load chute 26 adjacent theworkpiece transfer mechanism 20. The workpiece transfer mechanism 20includes a separator rod shown at 104 in FIGS. 1 and 3. The separatorrod 104 is supported adjacent the landing portion 28 of the load chute26. The separator rod 104 pushes each unformed workpiece 16, one at atime, from the landing portion 28 of the load chute 26 into a stagingposition 106 adjacent the grip jaws 72. The separator rod 104 thenretracts and an injector assembly, generally indicated at 108 in FIGS. 1and 3, pushes each unformed workpiece 16, one at a time, from thestaging position 106 into a grip position between the open grip jaws 72.Each newly injected workpiece 16 strikes a newly formed workpiece 16still disposed between the grip jaws 72 and forces the newly formedworkpiece 16 onto the declined exit chute 22. Each newly formedworkpiece 16 slides down the declined exit chute 22 and into a bin.

The injector assembly 108 includes between one and four horizontalinserter rods 110 removably attached along a vertical support rod 112.After each unformed workpiece 16 has been deposited in the stagingposition 106, the inserter rods 110 are driven axially into the unformedworkpiece 16, pushing the unformed workpiece 16 into the grip positionbetween the grip jaws 72. The number of inserter rods 110 used dependson the length of the workpieces 16 in a given parts run. The longer theworkpiece 16, the greater the number of inserter rods 110 attached tothe vertical support rod 112.

The workpiece transfer mechanism 20 also includes a pivot linkage, shownat 114 in FIG. 1, that connects the separator rod 104 and injectorassembly 108 to the piston rod 38 through a rectangular window (notshown) in the cylindrical portion 86 of the lower piston 50. This pivotlinkage 114 uses the downward motion of the upper piston 46 to drive theseparator 104 and inserter rods 110 of the transfer mechanism 20. Drivenby the pivot linkage 114, the transfer mechanism 20 simultaneouslyintroduces an unformed workpiece 16 between the jaws 72 of the gripchuck 12 and ejects a completed workpiece 16 to the exit chute 22.

It is the first portion of the downward motion of the piston shaft 38that the pivot linkage 114 transfers to the separator 104 and inserterrods 104, 110. Because the pivot linkage 114 uses the first portion ofthe downward forming stroke motion, the transferred motion is relativelyrapid. This is because the motion of the upper piston 46 and piston rod38 are not hydraulically dampened during the first portion of theforming stroke and the workpiece 16 is not yet in contact with theforming tool 18. Therefore, although the upper piston 46 slows in itsdownward movement when the forming tool 18 contacts and is forming theworkpiece 16, this resulting slower motion of the piston rod 38 does notlimit the speed at which the transfer mechanism 20 inserts individualworkpieces 16.

A rotator, generally indicated at 116 in FIGS. 1 and 2, is operativelyconnected to the tool 18 to rotate the tool 18 about the forming axis14. The rotator 116 includes a cylindrical spindle and case, shown at118 and 120, respectively, in FIG. 2. The spindle 118 is rotatablysupported on the forming axis 14 within the cylindrical case 120. Therotator 116 also includes a Reliance electric spindle motor (part no.PZIF1005), shown at 122 in FIG. 1, is drivingly connected to the spindle118 through a Reeves drive system (part no. R376281001) 124. The motor122 is drivingly connected to the spindle 118 through the drive system124.

The forming tool 18 is supported on the spindle 118 to rotate the tool18 about the forming axis 14 in the path of workpieces 16 being loweredalong the forming axis 14 by the grip chuck 12 and the compoundhydro-pneumatic cylinder 30. The forming tool 18 includes a generallyflat-based dome-topped circular tool adapter head generally indicated at126 in FIGS. 1, 2, 4, 5 and 9. As is best shown in FIGS. 4 and 5 thetool adapter head 126 is configured to releasably engage formingimplements 128. The tool adapter head 126 fastens at its base to the topof the spindle 118.

The tool adapter head 126 includes a pair of cutter receptacles, shownat 130 in FIGS. 4 and 5, for releasably engaging forming implements 128such as cutter blocks 132 supporting carbide cutting blades 134. Whencutter blocks are fastened into the receptacles, the cutting blades 134are disposed adjacent the forming axis 14 in a position to cut one endof a workpiece 16 held in the grip jaws 72 as the grip chuck 12approaches the proximate position. The cutting blades 134 are positionedto cut a tapered conical tip on a cylindrical workpiece 16 insertedaxially downward between the blades 134 as shown in FIG. 9.

The tool adapter head 126 accepts cutter blocks 132 having cuttingblades 134 that are twice the size of standard cutting blades used withworkpiece-pointing machines. The larger cutting blades 134 producebigger chips & less heat while cutting. The larger cutting blades 134absorb more heat energy during cutting than would small cutter bladesbecause the larger blades 134 cut larger chips from the workpieces 16.By cutting larger chips there is less friction and therefore lessfrictional heat generated for a given mass of chips. The amount of heatenergy retained within the larger metal fragments removed from theworkpiece together with the amount of heat energy retained in the largercutting tool 18 eliminates the need to cool each workpiece 16 aftercutting.

As shown in FIG. 5 the tool adapter head 126 also includes a chuckreceptacle 136 for releasably engaging a collet chuck 138 configured tointerchangeably hold hole-forming implements 128 such as drill bits 140,broachers (not shown), reamers (not shown) and the like. The colletchuck 138 is a Series GM70 spring collet chuck available from ETM underCollet Chuck Cat. No. 690099. The chuck receptacle 136 includes acircular chuck shaft formed coaxially into the tool adapter head 126 andhaving a diameter slightly greater than the 5/8" shank diameter of thecollet chuck 138 to slidably receive the collet chuck 138 within theshaft. A diagonal screw shaft shown at 142 in FIG. 5 extends inward froman upper surface of the tool adapter head 126 and intersects the chuckshaft. A lower end of the screw shaft is interiorly threaded. A setscrew 144 is disposed within the diagonal screw shaft 142 in threadedengagement with the screw shaft 142 and can be advanced down the screwshaft 142 to anchor the collet chuck 138 within the collet shaft.

When a drill bit 140 is clamped in the rotating collet chuck 138, thebit 140 is aligned with the forming axis 14. On each forming stroke, thebit drills a hole into one end of a workpiece 16 held in the grip jaws72 as the grip chuck 12 approaches the proximate position relative tothe forming tool 18. Similar to a drill bit 140, when a broacher isclamped in the collet chuck 138, the broacher is aligned with theforming axis 14. During each forming stroke, the broacher broaches ahole previously formed in one end of a workpiece 16 held in the gripjaws 72 as the grip chuck 12 approaches the proximate position.

When drill bits and other such tools are used, they will generallyproject upward through an aperture 250 in a disk-shaped rotator cover252 as shown in FIG. 2. A pair of diametrically opposed fiber optic eyes254 are disposed within an inner circumference of the aperture 250. Whenan upwardly projecting tool, such as a drill bit, breaks, light will beable to pass from one of the eyes 254 to the other completing a fiberoptic circuit and signalling an electronic controller to shut down themachine 10.

The apparatus 10 includes an electronic controller in the form of aprecision logic control (PLC) 146 programmed to detect workpieces 16that lack a previously formed hole. When a forming implement that altersthe configuration of a previously formed hole in a workpiece 14 (such asa broacher or a reamer) is installed in the collet chuck 138, the PLC146 will detect and reject defective workpieces 16 that lack holes. ThePLC 146 is programmed to detect and reject workpieces 16 that arepresent in the grip jaws 72 whenever the forming stroke takes longerthan a predetermined maximum time. When the forming stroke takes toolong it generally indicates that the broacher or reamer has encountereda workpiece surface without a hole to broach or ream and thehydro-pneumatic cylinder 30 has stalled.

The PLC 146 ejects defective workpieces by signaling a wastegate, shownat 147 in FIG. 13, in the exit chute 22 to open. As the defectiveworkpieces slide down the exit chute 22 they strike the wastegate 147.The wastegate 147 deflects defective workpieces causing them to fallfrom the chute 22 through a waste chute 149 and into a waste bin 151. Toactuate the wastegate 147 the PLC 146 signals a solenoid air valve 153to send pressurized air to an air cylinder 155. The air cylinder 155 isconnected to an arm 157 of the wastegate 147 and causes the wastegate147 to pivot around a pivot point 159. As the wastegate 147 pivots, adiverter portion 161 of the wastegate 147 swings into the exit chute 22.

As shown in the block diagram of FIG. 11, the PLC 146 includes an AllenBradley SLC 5/01 processor 230 and a Panelview 550 operator interface232 with an LCD display. The PLC is enclosed in a 24"×24"×8" electricalenclosure shown at 234 in FIG. 1. Also included in the PLC assembly 146but not shown in the Figures are a 4-slot I/O rack, a 16 pt. DC inputcard, a 16 pt. AC output card, a 42 watt rack-mounted power supply, a750VA control transformer, a 12 AMP motor contactor (IEC style) with anoverload relay, a 24V, 4.8 AMP DC power supply, and a 30 AMPthrough-the-door disconnect/breaker switch. All machine functions,including wastegate 147 operation, are initiated and/or controlled bythe use of soft keys on the Panelview as shown in FIG. 11.

The apparatus 10 also includes a chip and heat removal system thatobviates the need for a fluid bath. The chip and heat removal systemincludes the large cutting blades 134 described above and a centrifugalfan portion 148 of the spindle 118 disposed beneath and rotatingcoaxially with the tool adapter head 126. In addition, timed air frompneumatic cylinder exhaust is directed to contain the chips in theremoval system. A portion of the fan is shown at 148 in FIG. 2. The fan148 and pressurized air force metal fragments from the forming tool 18out of the spindle 118 through a hole (not shown) in the cylindricalcasing 120 of the spindle 118. From the hole, the fan blows the chipsalong a length of flexible hose shown at 150 in FIG. 1 and into acooling chamber (not shown).

The apparatus 10 includes the positive stop 40 to prevent workpieces 16from overshooting the proximate position as the forming tool 18 isforming them. In other words, the positive stop 40 consistently arrestsdownward cutting motion at the same point so that forming depth will notvary with air pressure or speed.

The reciprocating stop surface 42 is a flat annular surface disposed ona reciprocating stop in the form of a metallic knurled ring shown at 152in FIGS. 2 and 7-9. The knurled ring 152 is adjustably connected to thereciprocating portion 32 of the apparatus 10. More specifically, theknurled ring 152 is disposed in threaded engagement around an exteriorlythreaded portion 154 of the cylindrical portion 86 of the lower piston50. The position of the knurled ring 152 relative to the reciprocatingportion 32 is therefore adjustable in a direction parallel to theforming axis 14. An operator can lengthen the forming stroke and therebyincrease the forming depth on each workpiece 16 by turning the knurledring 152 and moving it upward along the cylindrical portion 86 of thelower piston 50. Conversely, an operator can shorten the forming strokeand depth by moving the knurled ring 152 downward.

The reciprocator includes a lower limit switch, generally indicated at156 in FIGS. 7-9, disposed in the path of the knurled ring 152 adjacentthe stationary stop surface 44. The lower limit switch 156 is actuableby contact with the knurled ring 152 when the reciprocating portion 32of the apparatus 10 is in the extended position. The lower limit switch156 is configured to send a signal in response to actuation that causesthe compound hydro-pneumatic cylinder 30 to reverse direction,initiating the return stroke.

The lower limit switch 156 is supported on a tool steel block generallyindicated at 158 in FIGS. 2 and 6-9. The cylindrical portion 86 of thelower piston 50 is disposed concentrically within a circular shaft,shown at 160 in FIG. 6, that extends vertically through the approximatecenter of the block 158 from a top surface of the block 158 to a bottomsurface of the block 158. The top surface of the block 158 is also thestationary stop surface 44 of the positive stop 40. The diameter of thecircular shaft 160 is sufficiently large to prevent the block 158 fromcontacting the cylindrical portion 86 of the lower piston 50 as thelower piston 50 travels up and down along the forming axis 14.

The block 158 has a rectangular channel 162 formed into its bottomsurface. The channel 162 is sized to allow the block 158 to sit astridethe stationary bronze guide plate 62. The block 158 is fastened to thebronze guide plate 62 by four fasteners (not shown) through fourfastener holes 164. A back side of the block 158 includes a switchrecess 166 shaped to receive and support the lower limit switch 156. Asis best shown in FIG. 6, a circular aperture 168 extends downward fromthe upper surface 44 of the block 158 to intersect the switch recess166. The lower limit switch 156 includes an actuator button, shown at170 in FIGS. 7 and 8, that extends upward from a stationary switch body172 of the lower limit switch 156 through the aperture 168 in thestationary stop surface 44. An upper portion of the actuator button 170protrudes vertically from the circular aperture 168, above thestationary stop surface 44.

As explained above, the presence of the positive stop 40 preventsworkpiece overshoot. The positive stop 40 also prevents workpieceundershoot by allowing the lower limit switch 156 to be supported in ahigher position. Higher placement of the lower limit switch 156 insuresthat the reciprocating stop surface 42 will always hit the stationarystop surface 44 before the compound hydro-pneumatic cylinder 30reverses--even at extremely slow reciprocation rates. Without thepositive stop 40, the lower limit switch 156 must be placed at a lowerintermediate position where an average reciprocating speed will resultin a desired forming depth on each workpiece 16. With no positive stopto force a consistent reversal position, as the forming tool 18 dullsand the compound hydro-pneumatic cylinder 30 slows, the forming strokewill grow gradually shorter resulting in shallower workpiece 16 formingdepths.

The apparatus 10 also includes an upper limit switch, shown at 174 inFIG. 1, supported on the stationary support frame 36 adjacent theworkpiece transfer mechanism pivot linkage 114. A switch actuator fork176 is fastened to a pivot shaft 178 of the pivot linkage 114 thatextends through the support frame 36. The actuator fork 176 and upperlimit switch 174 are positioned so that the pivot linkage 114 will causethe actuator fork 176 to actuate the upper limit switch 174 when theupper piston 46 reaches the top of its return stroke.

In operation, the air diverter valve 78 responds to upper limit switch174 actuation by directing air through the upper air inlet tube 76 intothe upper portion of the pneumatic cylinder 48 above the upper piston46. This pneumatic pressure forces the upper piston 46 downward,initiating the forming stroke. During an initial portion of the formingstroke the upper piston 46 is driven rapidly downward without hydraulicdampening and with the lower piston 50 and grip chuck 12 remainingstationary. During this rapid undampened portion of the forming strokethe piston rod 38 and plunger 68 are driven downward and the pivotlinkage 114 between the piston rod 38 and the transfer mechanism 20positions an unformed workpiece 16 between the jaws 72 of the grip chuck12. As the plunger 68 continues downward it forces the grip jaws 72downward and into the gripped position--driving the jaws 72 over-centerand clamping the unformed workpiece 16 between the jaws 72. As the jaws72 clamp the workpiece 16 a lower surface of the plunger 68 may bebrought to bear on the head of the unformed workpiece 16.

At this point the upper piston 46, piston rod 38 and plunger 68 continuetheir downward travel but also begin driving the grip chuck 12 and lowerpiston 50 downward. The lower piston 50 begins to move because, asdescribed above, the lower piston 50 is secured to the grip chuck crossbar 66. As the lower piston 50 is drawn downward, hydraulic fluid isforced from the annular chamber 88 into the air-pressurized hydraulicreservoir 98 through the hydraulic tube 94 and valve 102. Therefore,during the final portion of the forming stroke the motion of theunformed workpiece 16 is hydraulically dampened as the workpiece 16engages the forming tool 18.

At the completion of the downward forming stroke the knurled ring 152 ofthe positive stop 40 depresses the lower limit switch actuator button170, actuating the lower limit switch 156. The lower limit switch 156sends an electrical signal to the solenoid within the air diverter valve78, causing the diverter valve 78 to direct pressurized air through thelower air inlet tube and into the lower portion of the pneumaticcylinder 48. Either simultaneous with lower limit switch 156 actuationor shortly thereafter, the knurled ring 152 contacts the stationary stopsurface 44, ending the downward forming stroke. The pressurized airflowing into the lower portion of the pneumatic cylinder 48 then beginsto drive the upper piston 46 upward, initiating the return stroke.

As the upper piston 46 moves upward on the initial portion of the returnstroke it carries with it the piston rod 38, the plunger, the grip chuck12, the newly-cut workpiece 16 and the lower piston 50. As the lowerpiston 50 moves upward it draws hydraulic oil through the hydraulic linefrom the hydraulic reservoir 98 and into the expanding annular chamber88. After the lower piston 50 and grip chuck cross bar 66 have reachedthe upper limit of their travel, and with the grip chuck cross bar 66contacting the stationary bronze guide plate 62, the plunger continuesto pull the jaws 72 of the grip chuck 12 upward. The plunger pulls thejaws 72 over-center which causes the jaws 72 to release the newly-cutworkpiece 16. As the upper piston 46 reaches the end of the returnstroke, the upper limit switch 174 is actuated through the pivot linkage114, re-initiating the downward forming stroke and workpiece transfer.

During the fastener forming process, the compound hydraulic-pneumaticcylinder 48 provides vertical workpiece 16 movement that issubstantially faster than the movement that the cams or chains ofstandard mechanical devices can provide. Because the forming process isfaster, the forming tool 18 does not require lubricant. The hydrauliccylinder 52 also extends the life of the forming tool 18 by acting as ashock-absorbing cushion during the forming process and during downwardmovement of the workpiece into the forming tool 18. While somehydraulically-dampened systems may lack precision due to undershoot andovershoot problems, the positive stop 40 allows operators to preciselyand consistently control forming stroke length.

Cycle time is the sum of the total time it takes to load and cut eachworkpiece 16. The cutting feed rate is preset and is limited by themaximum speed at which a workpiece 16 can be fed into the forming tool18 and effectively formed. However, the non-forming, or "workpiecetransfer" portion of the cycle is both manually adjustable andself-regulating. An operator can, therefore, change the overall cyclespeed by increasing or decreasing the part transfer speed, i.e., thespeed at which the workpiece transfer mechanism 20 feeds individualunformed workpieces 16 into the forming tool 18. The speed of theworkpiece transfer portion of the cycle is dependent on cutting load,pneumatic pressure, and the size of a one-way restricting variableorifice within the dampening valve 102. Workpiece transfer rate isincreased by higher pneumatic input pressure to the compound cylinder30, reduced cutting load, and/or increased dampening valve 102 orificesize. Conversely, workpiece transfer rate is decreased by lowerpneumatic input pressure, higher cutting loads, and/or decreaseddampening valve orifice size. The pneumatic input pressure is typicallyset at 100 psi. However, the system will operate with input pressures aslow as 60 psi. Operators typically adjust the workpiece transfer rate byadjusting the dampening valve 102. This changes the size of the orificein the dampening valve 102 and therefore the rate at which the lowerpiston 84 can force hydraulic oil from the annular chamber 88 of thehydraulic cylinder 52 into the air-pressurized oil reservoir 98 as thereciprocating portion 32 of the apparatus 10 moves downward on a formingstroke.

The apparatus 10 includes a height adjuster connected between theforming tool 18 and the gripper 12. The height adjuster is configured toallow an operator to adjust forming depth by adjusting the relativedistance between the forming tool 18 and gripper 12 as measured alongthe forming axis 14 in the proximate position. By operating the heightadjuster, an operator can adjust the relative distance between theforming tool 18 and gripper 12 by adjusting the height of the rotator116 that carries the forming tool 18.

The height adjuster allows a forming machine constructed according tothe present invention to accommodate different length workpieces 16. Italso improves service access to the forming tool 18 by allowing anoperator to easily lower the rotator 116 and forming tool 18 to theposition shown in FIG. 1.

As is shown in FIGS. 1 and 10, the height adjuster includes a pneumaticslide lift 180. The pneumatic slide lift 180 includes an air holdingcylinder 182 and a pneumatic cylinder 184 that support the support frame36 above a base 186. A slide bracket 188 is slidably mounted forvertical movement on the air holding cylinder 182 and the pneumaticcylinder 184. The rotator 116 and forming tool 18 are supported on theslide bracket 188 as is best shown in FIG. 1. A threaded heightadjustment stop rod 190 is threaded through a portion of the supportframe 36 and extends vertically downward to abut an upper surface 192 ofthe slide bracket 188. As is explained in greater detail below, theslide bracket 188 is upwardly biased by pressurized air 193 andhydraulic fluid 194 within the cylinders 182, 184 and is adjustably helddown by the stop rod 190, i.e., an upwardly directed hydro-pneumaticbiasing force. When an operator screws the rod downward using a ratchetshown at 196 in FIGS. 1 and 10, the slide bracket 188 is moved downwardagainst the upward hydro-pneumatic biasing force. When an operator usesthe ratchet 196 to screw the stop rod 190 upward, the biasing forcedrives the slide bracket 188 upward. In this way the height of theforming tool 18 is vertically adjustable relative to the grip chuck 12to accommodate various workpiece lengths.

The slide lift 180 also includes a telescoping vertical center supportcylinder generally indicated at 198 in FIG. 10. The center supportcylinder 198 is connected between the base 186 and the slide bracket 188between the air holding cylinder 182 and the pneumatic cylinder 184 asshown in FIG. 10. The air holding cylinder 182, pneumatic cylinder 184and a lower stationary portion 200 of the telescoping center supportcylinder 198 are fixed to the base 186. The support frame 36 isvertically supported on an upper telescoping portion 202 of the centersupport cylinder 198. The upper telescoping portion 202 of the centersupport cylinder 198 is slidably supported on the lower stationaryportion 200. A fluid seal is disposed between the upper telescopingportion 202 and the lower stationary portion 200. The pneumatic cylinder184 contains a single annular piston 204 disposed between an uppercylinder region 206 filled with pressurized air and a lower cylinderregion 208 filled with hydraulic oil. The air holding cylinder 182serves as an air reservoir and is in fluid communication with the uppercylinder region 206 through a solenoid operated air valve 210. Ahydraulic channel 212 between the lower cylinder region 208 and thetelescoping support cylinder 196 allows hydraulic oil to flow freelybetween the lower cylinder region 208 and the support cylinder 196. Whenthe stop rod 190 is retracted upward, the constant downward pressureexerted by the air from the air holding cylinder 182 causes hydraulicoil to flow from the lower cylinder region 208 and into the telescopingcenter support cylinder 196. As the oil passes into the support cylinder196 it forces the upper telescoping portion 202 of the center supportcylinder 196 to move upward, carrying with it the slide bracket 188.

The forming tool 18 and rotator 116 may be lowered to a fully downposition shown in FIG. 1 without advancing the stop rod 190 downward.This is accomplished by releasing the air charge from the air holdingcylinder 182 and opening the solenoid air valve 210 to allow air to flowout of the upper cylinder region 206. This allows the piston 204 to moveupward in the pneumatic cylinder 184 which allows hydraulic oil to movefrom the support cylinder 196 to the lower cylinder region 208 of thepneumatic cylinder 184. As a result, the telescoping portion 202 of thecenter support cylinder 196 moves downward, carrying with it the slidebracket 188 and rotator 116.

The apparatus 10 includes a removable sorter attachment comprising anelectrically-conductive detection ring coaxially supportable on theforming tool 18 in a position coaxially aligned with and spaced from thepart gripper 12. The detection ring is pre-selected to have an innerdiameter slightly larger than an outer diameter of workpieces 16 to besorted. The detection ring is configured to encircle a portion of arelatively straight workpiece 16 held in the gripper 12 when the gripper12 and detection ring are in the proximate position, the workpiece 16being withdrawn from the detection ring when the gripper 12 anddetection ring are in the remote position. The detection ring, thesupport frame 36, the reciprocator, the gripper 12 and a workpiece 16held in the gripper 12 define an electrical circuit. The circuit iscompleted when a workpiece 16 contacts the detection ring. An electricalpower source is connected into the circuit. An electrically actuatedbent workpiece diverter is also connected into the circuit. Theworkpiece diverter includes the wastegate 147, the solenoid air valve153 and the air cylinder 155 shown in FIG. 13. The workpiece diverter isoperable to shunt bent workpieces 16 away from the exit chute 22 (asdescribed above in connection with the PLC description) when the bentworkpieces 16 contact the detection ring and complete the electricalcircuit.

The description and drawings illustratively set forth our presentlypreferred invention embodiments. We intend the description and drawingsto describe these embodiments and not to limit the scope of theinvention. Obviously, it is possible to modify these embodiments whileremaining within the scope of the following claims. Therefore, withinthe scope of the claims, one may practice the invention otherwise thanas the description and drawings specifically show and describe.

We claim:
 1. In a fastener forming apparatus for forming fasteners fromcylindrical workpieces, the apparatus comprising:a workpiece grippersupported on a forming axis and configured to releasably grip and carrya generally cylindrical workpiece in a coaxial disposition along theforming axis; a forming tool spaced from the gripper along the formingaxis; at least one of the workpiece gripper and tool supported forrelative reciprocal motion along the axis between a remote position anda proximate position, the gripper and tool disposed farther apart in theremote position than in the proximate position; a workpiece transfermechanism configured to sequentially transfer a series of workpiecesinto the workpiece gripper and to drive preceding workpieces out of theworkpiece gripper and onto an exit path; a reciprocator operativelyconnected to a reciprocating portion of the apparatus, the reciprocatingportion of the apparatus comprising one of the workpiece gripper andtool, to drive one of the workpiece gripper and tool between theextended and retracted positions, the reciprocator having a stationaryend connected to a stationary support and a reciprocating endoperatively connected to the reciprocating portion of the apparatus, thestationary end being hydro-pneumatically coupled to the reciprocatingend, the motion of the reciprocating end and the reciprocating portionof the apparatus being hydraulically dampened; the improvementcomprising: a positive stop including a reciprocating stop surfacedisposed on the reciprocating portion of the apparatus in a position toengage a stationary stop surface when the workpiece gripper and tool arein the proximate position to prevent the reciprocator from causing thereciprocating portion of the apparatus to overshoot or undershoot theextended position.
 2. A fastener forming apparatus as defined in claim 1in which the reciprocating stop surface is disposed on a reciprocatingstop that is adjustably connected to the reciprocating portion of theapparatus, the position of the reciprocating stop relative to thereciprocating portion of the apparatus being adjustable in a directionparallel to the forming axis.
 3. A fastener forming apparatus as definedin claim 1 in which the reciprocator includes a lower limit switchdisposed in the path of the reciprocating portion of the apparatus, thelower limit switch being actuable by contact with the reciprocatingportion of the apparatus in the extended position, the lower limitswitch configured to signal the reciprocator to reverse direction inresponse to lower limit switch actuation.
 4. A fastener formingapparatus as defined in claim 3 in which the lower limit switch issupported adjacent the stationary stop.
 5. A fastener forming apparatusas defined in claim 4 in which the lower limit switch includes a plungeractuator that extends through an aperture in the stationary stopsurface.
 6. A fastener forming apparatus as defined in claim 1 in whichthe reciprocator includes a compound hydro-pneumatic cylinder connectedbetween the stationary end and the reciprocating end of thereciprocator.
 7. A fastener forming apparatus as defined in claim 6 inwhich the hydro-pneumatic cylinder is connected to a stationary supportand includes a reciprocating piston rod that extends from a pistonportion of the cylinder and operatively connects the cylinder to theworkpiece gripper.
 8. A fastener forming apparatus as defined in claim 1in which reciprocal motion of the reciprocator drives the workpiecetransfer mechanism.
 9. A fastener forming apparatus as defined in claim1 in which the assembly includes a height adjuster connected between theforming tool and the gripper and configured to adjust the relativedistance between the forming tool and the gripper as measured along theforming axis in the proximate position.
 10. In a fastener formingapparatus for forming fasteners from cylindrical workpieces, theapparatus comprising:a workpiece gripper supported along a forming axisand configured to releasably grip and carry a generally cylindricalworkpiece in a coaxial disposition on the forming axis; a forming toolspaced from the gripper along the forming axis; at least one of theworkpiece gripper and tool supported for relative reciprocal motionalong the axis between a remote position and a proximate position, thegripper and tool disposed farther apart in the remote position than inthe proximate position; a workpiece transfer mechanism configured tosequentially transfer a series of worpieces into the workpiece gripperand to drive preceding workpieces out of the workpiece gripper and ontoan exit path; a reciprocator operatively connected to a reciprocatingportion of the apparatus, the reciprocating portion of the apparatuscomprising one of the workpiece gripper and tool, to drive one of theworkpiece gripper and tool between the extended and retracted positions,the reciprocator having a stationary end connected to a stationarysupport and a reciprocating end operatively connected to thereciprocating portion of the apparatus, the stationary end beinghydro-pneumatically coupled to the reciprocating end, the motion of thereciprocating end and the reciprocating portion of the apparatus beinghydraulically dampened; a rotator operatively connected to one of theworkpiece gripper and the tool; the improvement comprising:the formingtool including a hole-forming implement.
 11. A fastener formingapparatus as defined in claim 10 further including a positive stopincluding a reciprocating stop surface disposed on the reciprocatingportion of the apparatus in a position to engage a stationary stopsurface when the workpiece gripper and tool are in the proximateposition.
 12. A fastener forming apparatus as defined in claim 10 inwhich the reciprocator includes a compound hydro-pneumatic cylinderconnected between the stationary end and the reciprocating end of thereciprocator.
 13. A fastener forming apparatus as defined in claim 12 inwhich the hydro-pneumatic cylinder is connected to a stationary supportand includes a reciprocating piston rod that extends from a pistonportion of the cylinder and operatively connects the cylinder to theworkpiece gripper.